Context: Urokodaki 鱗滝 gives Tanjirou 炭治郎 an unrealistic goal.
kono iwa wo kiretara {"saishuu senbetsu" ni iku} no wo kyoka suru この岩を斬れたら“最終選別”に行くのを許可する
If [you] cut this boulder, [I] will allow {[you] to go to the final selection}.
iwa tte {kiru} mono dakke? 岩って斬るものだっけ？
Was a boulder something [you] {cut}?
{katana de kireru} mono dakke? 刀で斬れるものだっけ？
Was it something {[you] can cut with a sword}?
{kireru} ki ga shinai 斬れる気がしない
[I] don't feel like {[I] can cut it}.
katana ga oreru...... 刀が折れる･･････
The sword will break......
